Bearing assemblies of the above-mentioned type are used in railway vehicle construction, such as in electric traction motors of railway vehicles, such as trains and streetcars. They are often configured as cylindrical roller bearings or as deep groove ball bearings. In such designs, the seal assembly is typically designed as a labyrinth seal so that friction remains low during operation of the bearing. In order to keep the rolling-element bearing in operational condition in an uninterrupted manner, the rolling elements must be supplied with lubricant, which can be provided as a lubricating grease or a lubricating oil.
According to a commonly-used design, the lubricating oil is led (supplied) directly from an adjacent transmission into the bearing assembly. That is, the lubricating oil is collected from the transmission and is supplied to the bearing assembly. Excess oil drains from the bearing assembly and is guided back into the transmission. In such a design, lattices having mesh widths in the range of 2-3 millimeters are disposed in the oil flow path in order to filter out at least large contaminants and to prevent such particles from getting into the rolling-element bearing. Then, the oil can be taken (suctioned out) from a location (oil pan) in the transmission where the oil settles.
Even at high rotational speeds and with high demands on operational performance, the same lubricating oil is still often utilized for both the transmission and the traction motor. Therefore, the oil circulating circuit and the lubricating oil often become contaminated due to passage through both the transmission and the traction motor. Furthermore, the traction motor then becomes very susceptible to loss of transmission oil. In case too much transmission oil is lost, bearing damage can result due to insufficient lubrication, which is a significant shortcoming of known traction motor designs.